Analysis of methane

Abstract

Methane is one of the end-products of ruminal fermentation, formed autotrophically by methanogenic archaea from CO2 and H2 derived from the fermentation of carbon sources, in particular sugars (5, 9, 14, 27). Methane is finally eliminated by belching, representing a loss of between 5 and 8% of the gross energy contained in the feedstuffs consumed by the animal (1). Methane is also considered a major source of greenhouse gas emissions from agriculture (13, 20). Methane has been measured in vivo by a number of techniques (1, 12, 13, 18). In vitro cultures allow for determination of methane production when different diets are fermented alone or in the presence of additives to study their responses on rumen fermentation (15, 19). The aim of this section is to describe the measurement of methane production from in vitro incubations inoculated with mixed ruminal microorganisms. Methane measurement from the following two in vitro systems will be described: i) batch cultures in sealed serum bottles (19) and ii) the fermenter called Rumen Simulation Technique (RUSITEC) that is a semi-continuous culture (3). The measurement of the methane production follows several steps: • Measurement of total gas production • Sampling of gas • Analysis of gas composition • Calculations. © 2007 IAEA.